Optimizing reclamation of data space

Abstract

An amount of storage to reclaim is determined based at least in part on a write size of new previous version data written most recently to a data region. The determined amount of storage is reclaimed.

1. A method of reclaiming storage, comprising:
 receiving a write size of previous version data written to a data region of a continuous data protection system; 
 determining, based at least in part on the write size, an amount of storage in the data region to reclaim; and 
 reclaiming at least the determined amount of storage in the data region. 
 
     
     
       2. The method of  claim 1 , wherein reclaiming is performed in the event a total amount of previous version data stored in the data region exceeds a threshold. 
     
     
       3. The method of  claim 1  further comprising:
 determining whether previous version data stored in a location being considered for reclamation is being used; and 
 in the event the previous version data stored in the location being considered for reclamation is being used, refraining from reclaiming the location being considered for reclamation until the previous version data stored in the location being considered for reclamation is no longer being used. 
 
     
     
       4. The method of  claim 1 , wherein reclaiming includes reclaiming a contiguous portion of the data region. 
     
     
       5. The method of  claim 1 , wherein reclaiming includes virtually reclaiming including by moving a pointer that references a position within the data region. 
     
     
       6. The method of  claim 5 , wherein reclaiming further includes physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 deleting a reference to the storage being reclaimed after updating the snapshot. 
 
     
     
       7. The method of  claim 5 , wherein reclaiming further includes physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 writing over previous version data stored in the storage being reclaimed after updating the snapshot. 
 
     
     
       8. A system for reclaiming storage, comprising:
 a processor; and 
 a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to:
 receive a write size of previous version data written to a data region of a continuous data protection system; 
 determine, based at least in part on the write size, an amount of storage in the data region to reclaim; and 
 reclaim at least the determined amount of storage in the data region. 
 
 
     
     
       9. The system of  claim 8 , wherein the processor is configured to reclaim in the event a total amount of previous version data stored in the data region exceeds a threshold. 
     
     
       10. The system of  claim 8  further comprising instructions which when executed cause the processor to:
 determine whether previous version data stored in a location being considered for reclamation is being used; and 
 in the event the previous version data stored in the location being considered for reclamation is being used, refrain from reclaiming the location being considered for reclamation until the previous version data stored in the location being considered for reclamation is no longer being used. 
 
     
     
       11. The system of  claim 8 , wherein the processor is configured to reclaim by reclaiming a contiguous portion of the data region. 
     
     
       12. The system of  claim 8 , wherein the processor is configured to reclaim by virtually reclaiming including by moving a pointer that references a position within the data region. 
     
     
       13. The system of  claim 12 , wherein the processor is further configured to reclaim by physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 deleting a reference to the storage being reclaimed after updating the snapshot. 
 
     
     
       14. The system of  claim 12 , wherein the processor is further configured to reclaim by physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 writing over previous version data stored in the storage being reclaimed after updating the snapshot. 
 
     
     
       15. A computer program product for reclaiming storage, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:
 receiving a write size of previous version data written to a data region of a continuous data protection system; 
 determining, based at least in part on the write size, an amount of storage in the data region to reclaim; and 
 reclaiming at least the determined amount of storage in the data region. 
 
     
     
       16. The computer program product of  claim 15 , wherein reclaiming is performed in the event a total amount of previous version data stored in the data region exceeds a threshold. 
     
     
       17. The computer program product of  claim 15  further comprising computer instructions for:
 determining whether previous version data stored in a location being considered for reclamation is being used; and 
 in the event the previous version data stored in the location being considered for reclamation is being used, refraining from reclaiming the location being considered for reclamation until the previous version data stored in the location being considered for reclamation is no longer being used. 
 
     
     
       18. The computer program product of  claim 15 , wherein the computer instructions for reclaiming include computer instructions for reclaiming a contiguous portion of the data region. 
     
     
       19. The computer program product of  claim 15 , wherein the computer instructions for reclaiming include computer instructions for virtually reclaiming including by moving a pointer that references a position within the data region. 
     
     
       20. The computer program product of  claim 19 , wherein the computer instructions for reclaiming further include computer instructions for physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 deleting a reference to the storage being reclaimed after updating the snapshot. 
 
     
     
       21. The computer program product of  claim 19 , wherein the computer instructions for reclaiming further include computer instructions for physically reclaiming the virtually reclaimed storage in the data region, including by:
 updating a snapshot by obtaining previous version data corresponding to a new baseline time stored in the data region and storing the obtained previous version data in a snapshot region; and 
 writing over previous version data stored in the storage being reclaimed after updating the snapshot.